The present invention disclosed herein relates to an electric device, a wireless power transmission device, and a power transmission method thereof.
Recently, the number of electric products in use, as well as their performance, have increased significantly. Specifically, due to the amazing advances in semiconductor and display technologies, portable electric devices have been miniaturized. However, portable electric devices have limitations in that they receive power through an electric wire. Although a charger is used to charge a product, after the product is used for a predetermined duration, it should be recharged through a wire, due to its limited charge capacity. To overcome this limitation, various wireless charging technologies are being developed. For example, portable electric devices may be charged using radio frequency (RF) or magnetic induction.
Specifically, use of magnetic induction charging of portable electric devices is exemplified in electric shavers produced by Philips Since supplying power wirelessly eliminates the possibility of electrical shorts caused by water, it can be safely used. In addition, eliminating cumbersome wires greatly contributes to aesthetic improvement of a product. However, magnetic induction has a very short charging range, which presents many inconveniences. To overcome the latter, wireless power transmission technologies that use radio frequency (RF) or resonant charging have emerged.
However, wireless power transmission technologies using RF have limitations in that power may be transmitted to only a preset direction because a device for focusing electric waves to a point is required. Also, it should be examined whether high-level RF signals pose harmful effects on health.